1. Field of Invention
The present invention relates to an antenna in a field of mobile communications, and more particularly to an antenna having al least two radiating patterns.
2. Description of Related Arts
A conventional dual-polarization omnidirectional antenna mainly adopts the combination of vertical polarization and horizontal polarization. Most of the conventional dual-polarization omnidirectional antennas accomplish omnidirectional beams by arranging several oscillators in a circle. Although the conventional technology of the dividing network has matured, the circular-polarization antenna usually has big volume, which complicates the structure of the antenna and leads to large difference in gains of the two polarizations. Therefore, the circular-polarization antenna is restricted in many application fields. Meanwhile, in the actual application, particularly in the field of mobile communications, the vertical-polarization and horizontal-polarization antenna is rarely used, while mostly an antenna polarized at ±45 degrees is used. For dual-polarization omnidirectional antennas, it is relatively difficult to accomplish a horizontal omnidirectional antenna, and thus it is more necessary to develop the dual-polarization omnidirectional antenna polarized at ±45 degrees.